gallivm: remove unused variable

Trivial.
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_tgsi.c b/src/gallium/auxiliary/gallivm/lp_bld_tgsi.c
index d7e92aa..c6b1dcb 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_tgsi.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_tgsi.c
@@ -527,8 +527,6 @@
    while (bld_base->pc != -1) {
       const struct tgsi_full_instruction *instr =
          bld_base->instructions + bld_base->pc;
-      const struct tgsi_opcode_info *opcode_info =
-         tgsi_get_opcode_info(instr->Instruction.Opcode);
       if (!lp_build_tgsi_inst_llvm(bld_base, instr)) {
          _debug_printf("warning: failed to translate tgsi opcode %s to LLVM\n",
                        tgsi_get_opcode_name(instr->Instruction.Opcode));